Leakage of Contaminated Water from the Upper Part of Tank C-1 in H-6 Tank Area


Print View Posted on: 24 December 2015

Event Date: 20 February 2014 Event Type: Power Reactor
Event Location: Japan, FUKUSHIMA-DAIICHI INES Rating: Not Applicable (Final)

At 23:25 (Japan time) on 19 February, 2014, TEPCO found that water was leaking from the upper part of Tank C-1 in H-6 Tank Area, which has stored the water that was condensed by RO (reverse osmosis desalination facility) after the treatment by SARRY (cesium removal facility), to the dike surrounding H-6 Tank Area and to the outside of the dike through the rainwater drainpipe running from the upper part of Tank C-1 to the ground surface beyond the dike.
At 05:40 (Japan time) on 20 February, 2014, TEPCO succeeded in stopping the water leakage by means of closing the valves installed between Tank C-1 and RO and transferring some amount of the water stored fully in Tank C-1 to other tanks in H-6 Tank Area.
The amount of water, which leaked to the outside of dike, was estimated to be approximately 100 m3.
The concentration of radioactive materials in the water leaked to the outside of the dike is as follows:
Cs-134: 4.2 kBq/L
Cs-137: 7.3 kBq/L
Co-60: 2.9 kBq/L
Sb-125: 41 kBq/L
Total Beta: 240 MBq/L
There has been no contamination of the ocean that raises any concern about influence to health and the environment.

INES Rating: Not applicable (Final) as per 16 April 2015
Release beyond authorized limits? No
Overexposure of a member of the public? No
Overexposure of a worker? No

Contamination spread within the facility? Yes
Damage to radiological barriers (incl. fuel damage) within the facility? No

Degradation of Defence In-Depth Yes

Person injured physically or casualty? No
Is there a continuing problem? No

Hiromitsu Yoneyama - Nuclear Regulation Authority
Nuclear Regulation Authority

hiromitsu_yoneyama@nsr.go.jp
http://www.nsr.go.jp/english/index.html
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